Maizatul Zolkapli

A free-space method for measurement of complex permittivity of double-layer dielectric materials at microwave frequencies

Two methods for the calculation of complex permittivity of double-layer dielectric materials measured by a spot-focusing free-space measurement system have been developed. Standard materials have been used to test these methods and further works will be carried out on SiO2 wafer. The dielectric constants obtained were close to the published values. The two methods developed are Transmission Method and Metal-Backed Method. The S11, S21, and S22 are measured for Transmission Method, while only S11 is measured for Metal-Backed Method. In both methods, the samples are sandwiched between two Teflon plates which are quarter wavelength at mid-band frequency. Results are reported in the frequency range of 18–26GHz.

Investigation on Elman neural network for detection of cardiomyopathy

Deterioration of structure and function of heart muscle is indicative of a degenerative disease known as cardiomyopathy. As a result, the hypertrophic condition of the heart often revealed itself in the form of abnormal sinus rhythm that can be detected via an electrocardiogram (ECG). In order to reduce the risk of misinterpretation by cardiologists, a variety of computational methods have been suggested for automated classification of arrhythmias. This paper proposes to explore Elman neural network for detecting cardiomyopathy. A total of 600 ECG beat samples were acquired from an established online database. Initially, the signals were filtered to eliminate high-frequency interference and perform baseline rectification. Nine time-based descriptors from leads I, II and III were used for training, testing and validation of the network structures. A total of five hidden-node node structures were tested with four different learning algorithms. Results show that all the network structure managed to achieve more than 90% classification accuracy. The fastest convergence was achieved with the Levenberg-Marquardt algorithm with an average of 16 epochs.

The design and development of automatic fish feeder system using PIC microcontroller

This research devoted to reduce the labor cost as well as develop better pellet dispense system. Subsequently, this research was proposed to design an automatic fish feeder system using PIC microcontroller application. The device developed combines mechanical and electrical system in controlling fish feeding activity. This device, basically consists of pellet storage, former, stand, DC motor and microcontroller. The pellets controlled by DC motor which located under the pellet storage. A control system was then attached to this device allowing the fish to be fed at the right cycle time as required or predefined by user. Timer was employed in this device to control the motor rotation attached to sphere former, which dispense the pellets into the water. The pellets dispensed into the marking area of the pond based solely on the rotation speed of the motor itself. The controller came with a keypad giving user more option in determining the suitable speed for the motor depends on their cattle. In short, the pellets in the automatic fish feeder system will be controlled by the rotation speed of DC motor.

pH sensing characteristics of silicon nitride thin film and silicon nitride-based ISFET sensor

The pH sensing characterizations of silicon nitride (Si₃N₄) thin film, and Si₃N₄-based ISFET sensor were discussed in this paper. The Si₃N₄ thin film was fabricated with to form silicon/silicon dioxide/silicon nitride (Si/SiO₂/Si₃N₄) structure while Si₃N₄-based ISFET was fabricated and packaged as a pH sensor. Both thin film and ISFET packaged device have low pressure chemical vapor deposited silicon nitride as sensing layer. Source measure unit (SMU), the semiconductor device analyzer model Agilent B1500A and a custom made test jig was used to investigate the electrical properties for both Si₃N₄ thin film and Si₃N₄-based ISFET sensor. The measurements were carrying out in three different buffer solutions with various pH levels of 4, 7 and 10 at room temperature. The pH sensitivity of thin film and ISFET packaged device with silicon nitride were 66.9 mV/pH and 53.6 mV/pH respectively. Both have shown good linearity in chosen pH range.

Fluorescence characteristic of ruthenium nanoparticles as a dissolved oxygen sensing material in gas and aqueos phase

The fabrication and characterization of a fiber optic dissolved oxygen sensor based on the dynamic quenching of fluorescence from a ruthenium complex in gas and aqueous phase is presented. The unclad portion of the multimode optical fiber is coated with an oxygen sensitive ruthenium complex, which is immobilized by the sol-gel route. The intensity of the fluorescence emission has been found to decrease as the oxygen content increases. The dynamic range and the temporal response of the sensor are investigated for three different environment, gas, deionized water and sea water. The performance of the device is evaluated in terms of the results obtained during actual measurements.

The development of Self-Service Restaurant Ordering System (SROS)

This paper is about The Development of Self-service Restaurant Ordering System (SROS). The manual restaurant ordering system is relies on a lot of manpower to handle all the process from taking order from customers, placing order, tidy up the table and cleaning the dishes. Therefore this system is developed to reduce the number of manpower in ordering task and at the same time reduce the monthly cost for the restaurant. Customer can make their order through the system and directly stored to the database. The system is designed using Microsoft Visual Studio 2008 and Microsoft Office Access 2007 to give a better solution for the manual system. A preliminary testing suggested that the SROS has a potential to replace the manual restaurant ordering system.

Design and fabrication of microfluidic transistor on silicon substrate

The fabrication and characterization of static microfluidic transistors on <100> p-silicon is demonstrated. A three photo mask level fabrication process, allows the construction of the microfluidic transistor with multiple channel widths which are 50μm, 100μm and 500μm. The basic device consists of two reservoirs connected via a channel which forms the basic fluidic circuit. Two doped regions will then be placed along the channel allowing the electrons to flow, comprising the electrical circuit. The results show that the fabrication technique used to build microfluidic transistors is relatively inexpensive and very much similar to present-day manufacturing technology that produces channel width ranging from 55 μm to 485 μm with depth ranging from 4.9 μm to 6.3 μm. Further work is carried out on the miniaturization of the micro-channel and the electrical characterization of the complete system.

Characterization of Inter Digital capacitor for water level sensor

This paper discussed about design and characterization of the Inter Digital capacitor. The main objective is to study the effects of width and spacing of the capacitor electrode on capacitance value. Water levels sensors are studied by using Inter Digital Capacitor (IDC) technique on Printed Circuit Board (PCB). IDC technique is used to make the capacitance measurement of the solution became more effective. This paper also presents simulation and experimental data to characterize the sensor. The result shows that the capacitance value is directly proportional to the electrodes width and inversely proportional to the electrodes spacing.

Design, fabrication and characterization of conductivity sensor using printed circuit board

This paper described about design, fabrication and characterization of conductivity sensor using printed circuit board (PCB). The main objective is to sense the conductivity of aqua agriculture. A sensor was design by using interdigital capacitor concept where the term interdigital refers to pattern of fingers that is resembled by the shape and relative position of the electrodes. This sensor was fabricated by using PCB in order to minimize the cost than the existing conductivity sensor. Sensor performance was characterized by various test setups to check ability and accuracy of the sensor. From the result, it shown that the sensor has very good sensitivity with correlation coefficient R2 of 0.969.

Bromophenol blue thin film coated fiber optic response towards pH sensing

The fabrication and characterization of a fiber optic pH sensor based on the evanescent wave absorption is presented in this paper. The sensor is prepared by coating the immobilized indicator in a sol-gel thin film onto the uncladded middle portion of a multimode plastic clad silica (PCS) fiber. The evanescent wave is used to selectively excite the indicator molecules within the fiber cladding for sampling the aqueous media surrounding the fiber. Changes in the pH of the analyte are detected by measuring the absorption spectrum of the sol-gel cladding in the sensing region of the optical fiber. pH buffer 1-14 were used to examine the response of the sensor. The sensor response and its dynamic range are reported for bromophenol blue (BPB) dye. The intensity of the absorption measured in the 470-850 nm spectral range has been found to increase as the pH value increases. The performance of the device is evaluated in terms of the results obtained during actual measurements.